The present invention relates to an oil seal device for a high-speed rotary machine such as turbochargers.
In FIG. 1 is shown a prior art oil seal device for a high-speed rotary machine. A floating metal bush b is mounted on a casing a and is pressed against a rotating shaft c. The rotating shaft c is formed with an oil thrower d and an annular groove e into which is fitted a seal ring f. A lubricating oil is supplied through an oil passage g formed in the casing a, lubricates the floating metal bush b and is directed to flow into spaces h and i on both sides of the floating metal bush b.
The lubricating oil which flows into the space i can flow further to a discharge port (not shown), but the lubricating oil which flows into the space h tends to leak into the space j outwardly of the seal ring f. The lubricating oil is thrown outwardly by the oil thrower d rotating at a high speed, and the oil which has not been thrown away and has passed past the oil thrower d is blocked by the seal ring f. However, depending upon the quantity of oil supplied through the oil passage g and the rotational speed of the shaft c, the seal ring cannot prevent the leakage of the oil. Especially in the case of a turbocharger, excessive leakage into the space j occurs when the pressure on the side of a turbine k (or a blower) is low. The prior art oil seal device has a further defect that after a long period of operation, carbon particles are accumulated between surfaces A and B of the casing a, forming the so-called carbon bridge which clogs the passage of oil. As a result, the flow or leakage of oil into the space j is accelerated so that the operation of the turbocharger cannot be continued.
The primary object of the present invention is therefore to provide an oil seal arrangement which can substantially solve the above-described problem, can ensure the stable sealing effects and can prevent the formation of carbon bridges at the oil thrower.
The present invention will become more apparent from the following description of a preferred embodiment thereof taken in conjunction with the accompanying drawings.